Technical Abstract:
Many Salmonella spp. have been shown to survive for long periods of time in the environment. Conversely, it is believed that S. choleraesuis, the host-adapted serotype in swine, does not survive well in the environment. We tested the survivability of S. choleraesuis in swine feces. Six pigs were infected with S. choleraesuis and feces was collected and pooled on days 2, 4, 7, and 10 postinoculation (PI). The feces was stored in a wet form (6 inches deep in a bucket, water added every 10 days) and a dry form (2 inches deep spread evenly in a pan and allowed to dry at room temperature). Salmonella choleraesuis was quantitated by the 5 tube MPN method. Salmonella choleraesuis was recovered from wet feces through 3 months, and from desiccated (dry) feces for at least 9 months. We also tested the infectivity of S. choleraesuis in dry feces. Pigs were inoculated at either 15 or 6 weeks of age with dry feces which had been stored either 3 or 4 months, respectively. Pigs were split into 2 groups and inoculated (approximately equal to 1 x 10**4 CFU/pig) either intranasally or by mixing dry feces with the swine ration and feeding it to the pigs. For all pigs, only mild clinical signs were observed. Additionally, the bacteria was found to be disseminated among the tissues of all pigs. These data suggest that S. choleraesuis can remain viable and infective in the environment and that passage through the host may affect virulence and/or survivability of S. choleraesuis in the environment. It also indicates that dried matter may be a reservoir for Salmonella and the removal of all organic matter should be emphasized in cleaning and sanitation management strategies.